Wireless communication devices, for example mobile devices, often have the capabilities to operate in different types of geographic and radio access networks. Mobile devices often have a preferred network, service provider, and/or radio access technology (RAT). The preferred choice often depends upon the cost of the service, contractual terms between the user and the service provider, the mobile device's capabilities, the present location of the mobile device, and/or other priority factors.
When a mobile device is switched ON, it starts scanning for available networks. Also, when scanning for a network, the mobile device must determine whether a found network supports the particular radio access technology used by the mobile device. In existing systems, if the acquired network or RAT or service provider is not the first choice, the mobile device often continues to scan, in hopes of finding a higher, more preferred choice. Existing multi-mode mobile devices are battery powered and can consume a great deal of energy searching for alternate networks while still operating in a particular network. Such scanning by the mobile station uses additional energy of the battery of the mobile device and also consumes valuable processing time.
Nowadays, the increasing number of networks having different RATs plus the increasing number of multi-mode mobile devices results in a longer scanning and registration time period. First, the number of available networks of different RATs in a particular geographic area has increased. Second, the number of RATs a single mobile device can access has increased. Thus, the numbers of possible matching combinations have increased (e.g., matching the mobile devices capabilities with the available networks in a particular geographic area). After the matching combinations have been determined, they are ranked based on a variety of preference factors and, finally, the highest priority network is selected for registration.
Even after an initial network is acquired, the mobile device must account for the possibility that it may be on the edge of coverage for one particular network and should therefore be ready for a network handoff. Since initial acquisition on a new network is often a time consuming process, taking many seconds per failed attempt and often multiple seconds for successful attempts, the multi-mode mobile device continuously looks for alternate networks on several different channels and multiple RATs which also consumes a lot of battery power.
Accordingly, there is a need for new scanning methods that can reduce the amount of time and power it takes to acquire an alternate wireless communication network for the mobile device capable of operating in multiple modes.
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The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.